1. Field of the Invention
This invention relates to compositions and processes for the treatment of wood in particular to render it fire retardant.
2. Background Information
In British Patent 761195 is described a process for flame proofing wood which comprises impregnating it with a solution of a tetrakis(hydroxymethyl) phosphonium (hereinafter called THP) salt and a poly functional organic nitrogen containing compound (or partially polymerized reaction product thereof) and further polymerizing it. Examples of the polyfunctional compound are urea and melamine and their methylolated and alkylated methylolated derivatives and use of urea, trimethylolmelamine and a partially methylated methylol melamine (product BT 309 of British Industrial Plastics) are exemplified. The pH of the impregnant solution may be adjusted with a carbonate or triethanolamine, which may also act as a catalyst, as may an acid. We have discovered that once an impregnant solution from a THP salt, urea, triethanolamine and partially methylated trimethylolmelamine has been prepared, it does not have a long life time because on standing it sets. This premature setting is a major problem because it reduces the lifetime of the impregnation bath liquid and hence the amount of wood that can be treated with that amount of liquid.